Fix the size of a StackHandleScope in art::CompilerDriver.

Change-Id: Id6fbbbbfc5dcf9920e630699d4c1afc1b86f858f
diff --git a/compiler/driver/compiler_driver.cc b/compiler/driver/compiler_driver.cc
index 47288b5..d352f39 100644
--- a/compiler/driver/compiler_driver.cc
+++ b/compiler/driver/compiler_driver.cc
@@ -1241,7 +1241,7 @@
   mirror::Class* referrer_class;
   mirror::DexCache* dex_cache;
   {
-    StackHandleScope<3> hs(soa.Self());
+    StackHandleScope<2> hs(soa.Self());
     Handle<mirror::DexCache> dex_cache_handle(
         hs.NewHandle(mUnit->GetClassLinker()->FindDexCache(*mUnit->GetDexFile())));
     Handle<mirror::ClassLoader> class_loader_handle(